What is known and what is still unknown within chronic musculoskeletal pain? A systematic evidence and gap map.

ABSTRACT: Evidence and gap maps (EGMs) can be used to identify gaps within specific research areas and help guide future research agendas and directions. Currently, there are no EGMs within the broad domain of chronic musculoskeletal (MSK) pain in adults. The aim of this study was to create a contemporary EGM of interventions and outcomes used for research investigating chronic MSK pain. This EGM was based on systematic reviews of interventions published in scientific journals within the past 20 years. Embase, PubMed, the Cochrane Library, and PsycINFO were used to retrieve studies for inclusion. The quality of the included reviews was assessed using AMSTAR-II. Interventions were categorised as either physical, psychological, pharmacological, education/advice, interdisciplinary, or others. Outcomes were categorised using the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) recommendations. Of 4299 systematic reviews, 457 were included. Of these, 50% were rated critically low quality, 25% low quality, 10% moderate quality, and 15% rated high quality. Physical interventions (eg, exercise therapy) and education were the most common interventions reported in 80% and 20% of the studies, respectively. Pain (97%) and physical functioning (87%) were the most reported outcomes in the systematic reviews. Few systematic reviews used interdisciplinary interventions (3%) and economic-related outcomes (2%). This contemporary EGM revealed a low proportion of high-quality evidence within chronic MSK pain. This EGM clearly outlines the lack of high-quality research and the need for increased focus on interventions encompassing the entire biopsychosocial perspective.

Participatory research: a Priority Setting Partnership for chronic musculoskeletal pain in Denmark.

OBJECTIVES: Patient and stakeholder engagements in research have increasingly gained attention in healthcare and healthcare-related research. A common and rigorous approach to establish research priorities based on input from people and stakeholders is the James Lind Alliance Priority Setting Partnership (JLA-PSP). The aim of this study was to establish research priorities for chronic musculoskeletal (MSK) pain by engaging with people living with chronic MSK pain, relatives to people living with chronic MSK pain, healthcare professionals (HCP), and researchers working with chronic MSK pain. METHODS: This JLA-PSP included a nation-wide survey in Denmark, an interim prioritisation, and an online consensus building workshop. The information gained from this was the basis for developing the final list of specific research priorities within chronic MSK pain. RESULTS: In the initial survey, 1010 respondents (91% people living with chronic MSK pain/relatives, 9% HCPs/researchers) submitted 3121 potential questions. These were summarised into 19 main themes and 36 sub-themes. In the interim prioritisation exercise, 51% people living with pain/relatives and 49% HCPs/researchers reduced the list to 33 research questions prior to the final priority setting workshop. 23 participants attended the online workshop (12 people/relatives, 10 HCPs, and 1 researcher) who reached consensus for the most important research priorities after two rounds of discussion of each question. CONCLUSIONS: This study identified several specific research questions generated by people living with chronic MSK pain, relatives, HCPs, and researchers. The stakeholders proposed prioritization of the healthcare system's ability to support patients, focus on developing coherent pathways between sectors and education for both patients and HCP. These research questions can form the basis for future studies, funders, and be used to align research with end-users' priorities.

Spatiotemporal patterns of pain distribution and recall accuracy: a dose-response study.

OBJECTIVES: Clinical decisions rely on a patient's ability to recall and report their pain experience. Monitoring pain in real-time (momentary pain) may reduce recall errors and optimize the clinical decision-making process. Tracking momentary pain can provide insights into detailed changes in pain intensity and distribution (area and location) over time. The primary aims of this study were (i) to measure the temporal changes of pain intensity, area, and location in a dose-response fashion and (ii) to assess recall accuracy of the peak pain intensity and distribution seven days later, using a digital pain mapping application. The secondary aims were to (i) evaluate the influence of repeated momentary pain drawings on pain recall accuracy and (ii) explore the associations among momentary and recall pain with psychological variables (pain catastrophizing and perceived stress). METHODS: Healthy participants (N=57) received a low (0.5 ml) or a high (1.0 ml) dose of hypertonic saline (5.8%) injection into the right gluteus medius muscle and, subsequently, were randomized into a non-drawing or a drawing group. The non-drawing groups reported momentary pain intensity every 30-s. Whereas the drawing groups reported momentary pain intensity and distribution on a digital body chart every 30-s. The pain intensity, area (pixels), and distribution metrics (compound area, location, radiating extent) were compared at peak pain and over time to explore dose-response differences and spatiotemporal patterns. All participants recalled the peak pain intensity and the peak (most extensive) distribution seven days later. The peak pain intensity and area recall error was calculated. Pain distribution similarity was determined using a Jaccard index which compares pain drawings representing peak distribution at baseline and recall. The relationships were explored among peak intensity and area at baseline and recall, catastrophizing, and perceived stress. RESULTS: The pain intensity, area, distribution metrics, and the duration of pain were lower for the 0.5 mL than the 1.0 mL dose over time (p<0.05). However, the pain intensity and area were similar between doses at peak pain (p>0.05). The pain area and distribution between momentary and recall pain drawings were similar (p>0.05), as reflected in the Jaccard index. Additionally, peak pain intensity did not correlate with the peak pain area. Further, peak pain intensity, but not area, was correlated with catastrophizing (p<0.01). CONCLUSIONS: This study showed differences in spatiotemporal patterns of pain intensity and distribution in a dose-response fashion to experimental acute low back pain. Unlike pain intensity, pain distribution and area may be less susceptible in an experimental setting. Higher intensities of momentary pain do not appear to influence the ability to recall the pain intensity or distribution in healthy participants. IMPLICATIONS: The recall of pain distribution in experimental settings does not appear to be influenced by the intensity despite differences in the pain experience. Pain distribution may add additional value to mechanism-based studies as the distribution reports do not vary with pain catastrophizing. REC# N-20150052.

Reducing the Weight of Spinal Pain in Children and Adolescents.

Spinal pain in adults is a significant burden, from an individual and societal perspective. According to epidemiologic data, spinal pain is commonly found in children and adolescents, where evidence emerging over the past decade has demonstrated that spinal pain in adults can, in many cases, be traced back to childhood or adolescence. Nevertheless, very little focus has been on how to best manage spinal pain in younger age groups. The purpose of this article is to put the focus on spinal pain in children and adolescents and highlight how and where these problems emerge and how they are commonly dealt with. We will draw on findings from the relevant literature from adults to highlight potential common pathways that can be used in the management of spinal pain in children and adolescents. The overall focus is on how healthcare professionals can best support children and adolescents and their caregivers in making sense of spinal pain (when present) and support them in the self-management of the condition.

Changes in Pain Sensitivity and Conditioned Pain Modulation During Recovery From Whiplash-associated Disorders.

OBJECTIVE: The objective of this study was to investigate the pain-sensory profile of patients with whiplash-associated disorders (WADs) prior and post 2 weeks of standardized rehabilitation and after a 6-month follow-up. MATERIALS AND METHODS: Twenty-two WAD participants (grade II; 14 women) and 22 sex-matched and age-matched healthy pain-free controls were enrolled. Pressure pain thresholds (PPTs) were assessed at local and distal muscles. Conditioned pain modulation (CPM) of PPTs was assessed using cuff pressure around the upper arm. Referred area of pain following supra-threshold pressure stimulation of the infraspinatus muscle was recorded on a body chart. Psychometric variables (pain intensity, area of perceived pain, pain catastrophizing, kinesiophobia, sleep problems, and depression level) were assessed. WAD group additionally completed the Neck Disability Index. RESULTS: The WAD group demonstrated lower local PPTs compared with controls at all time points (P<0.05) and lower distal PPTs at baseline and at 2 weeks when compared with 6 months (within-group) (P<0.05). The WAD group had a reduced CPM response and larger induced referred pain areas compared with controls (P<0.05), while no within-group changes were observed at any time point. The WAD group reported higher pain intensity and perceived area of pain compared with controls at all time points (P<0.05) and a mean Neck Disability Index score of 41% at baseline, 16% at 2 weeks, and 4% at 6 months. Furthermore, the WAD group reported improvements in all other psychometric variables (P<0.05), although only pain catastrophizing levels were comparable to controls at 2 weeks. DISCUSSION: PPTs but not CPM improved in the WAD group and were comparable to controls following 2 weeks following standardized rehabilitation, indicating that normalization of CPM may not be required to recover from WAD.

Pain referral area is reduced by remote pain.

BACKGROUND: Endogenous pain inhibitory mechanisms are known to reduce pain intensity, but whether they influence the size and distribution of pain referral is unclear. This study aimed to determine if referred pain is reduced by applying a remote, conditioning painful stimulus. METHODS: Twenty-four healthy men participated in this randomized, crossover study with a control and conditioning session. Referred pain was induced from the infraspinatus muscle (dominant side) by a painful pressure for 60 s. When applying pressure, the intensity was adjusted to a local pain intensity of 7/10 on a numerical rating scale. In the conditioning session, tonic painful pressure was simultaneously applied to the non-dominant leg during induction of referred pain. The area of referred pain was drawn onto a digital body chart and size extracted for data analysis. RESULTS: For the total group and in a subgroup with distinct patterns of referred pain (n = 15/24), the pain area perceived in the back and front+back was smaller during the conditioning compared with the control (p < 0.05). No significant difference was found between sessions in a subgroup only demonstrating local pain (n = 9/24). CONCLUSIONS: Engaging the descending noxious inhibitory control reduced the size of pain areas predominately when distinct pain referral was present. Assuming a conditioning effect of descending inhibitory control acting on dorsal horn neurons, these findings may indicate that mechanisms underlying pain referral can be modulated by endogenous control. The findings may indicate that referred pain may be a useful proxy to evaluate sensitivity of central pain mechanisms as previously suggested. SIGNIFICANCE: The current results indicate a link between endogenous inhibition and pain referral. Descending inhibitory control effects on pain referral support a spinal mechanism involved in pain referral. Future studies should investigate whether the spatial characteristics of referred pain (e.g. size, frequency of affected body regions and distribution away from the primary nociceptive stimulus) can useful to evaluate the efficiency of endogenous pain modulation.

Pain and Disability in Low Back Pain Can be Reduced Despite No Significant Improvements in Mechanistic Pain Biomarkers.

OBJECTIVE: Altered balance in nociception in response to noxious stimuli is commonly reported in chronic low back pain (LBP). However, it is unclear whether an improvement in the clinical presentation is contingent on a reduction in pain sensitivity. This study investigated whether the quantitative sensory testing (QST) profile changes in people undergoing rehabilitation for LBP. DESIGN: A prospective, observational case-control study. METHODS: Forty males and females, 18 to 40 years' old (20 with LBP) participated in 2 sessions. QST was performed at baseline and after discharge from rehabilitation (LBP) or after 3 to 8 weeks (controls). The QST battery consisted of determining pressure-pain thresholds at the low back and shoulder, temporal summation of pain, and conditioned pain modulation. Questionnaire data was used to determine pain (Numeric Rating Scale [NRS]), disability (Roland-Morris Questionnaire [RMQ]), Fear Avoidance Beliefs (FABQ), and The Örebro Musculoskeletal Pain Screening Questionnaire (ÖMPSQ) at baseline and discharge. The treatment effect was determined by calculating the Cohen d. RESULTS: No significant group×time interactions or main factor effect was found for any of the QST measures. The LBP group reported a significant reduction in NRS (P<0.0002, d=1.23), RMQ (P<0.0001, d=1.58), FABQ (P<0.001, d=0.87), and in the ÖMPSQ (P<0.00001, d=1.44). CONCLUSIONS: The results indicate that an improvement of clinical LBP is not contingent upon changes in the pain sensory profile. The value of screening pain sensitivity in LBP patients in primary care, needs to be investigated further, due to the patient population heterogeneity and the sensitivity of assessment methods.

Effect of a Posture-Cueing Shirt on Sitting Posture During a Functional Task in Healthy Participants: A Randomized Cross-Over Study.

OBJECTIVES: The purpose of this study was to investigate the effect of a posture-cueing shirt on sitting posture during a functional task. METHODS: Thirty healthy male participants were seated at a standardized workstation while completing 3 laptop writing tasks of 15-minute duration wearing either a posture-cueing shirt, a compression shirt, or no shirt. Posture was assessed based on photos taken at minutes 1 and 15 into the writing task from which the head and shoulder angles were measured and extracted for analysis. After each task, participants rated any potential pain they felt during the task on an 11-point numeric rating scale (NRS). RESULTS: The results showed that none of the shirts significantly affected the head or shoulder angles at any time point. Participants reported lower pain levels after using the posture-cueing shirt (NRS 0 [0-1]) compared with no shirt (NRS 1 [0-2]; P = .012). No significant difference in pain levels was observed between shirts. CONCLUSION: Although posture did not change in any conditions for these healthy male participants, the posture-cueing shirt resulted in a lower pain intensity compared with no shirt but not with a compression shirt. Although a significant difference was found for pain intensity favoring the posture-cueing shirt, this difference was negligible, and thus its value to reduce pain or improve posture in healthy participants remains in question.

Conditioned Pain Modulation Efficiency Is Associated With Pain Catastrophizing in Patients With Chronic Low Back Pain.

BACKGROUND: Previous studies have found a negative association between a conditioned pain modulation (CPM) response and pain catastrophizing among pain-free individuals. This study investigated the difference in CPM response between individuals with chronic low back pain (CLBP) and pain-free controls, and the association between pain catastrophizing and CPM response. METHODS: In all, 22 individuals with CLBP and 22 sex-matched and age-matched controls underwent a CPM protocol. Pressure pain thresholds (PPTs) were measured on the lower leg and lower back. The CPM response was registered as the change in PPT from baseline to after a cold pressor test (CPT). Catastrophizing was assessed using the Pain Catastrophizing Scale before the CPM protocol in both groups. RESULTS: Analysis of variance showed no interactions in PPT between groups and test sites at baseline or post-CPT. PPT increased significantly after CPT in the control group (P<0.006) but not in the CLBP group. The results showed significantly less pain inhibition participants with among participants with CLBP compared with controls (P<0.04). The CPM response was negatively associated with Pain Catastrophizing Scale scores in the CLBP group (rs=-0.67, P=0.0006) while no association was found in the control group. DISCUSSION: This study demonstrated a reduced CPM response and a negative association between pain inhibition and pain catastrophizing in individuals with CLBP. The results suggest that catastrophizing thoughts are associated with the efficiency of descending endogenous pain modulation in CLBP, although a causal relationship cannot be inferred.

Changing the Narrative in Diagnosis and Management of Pain in the Sacroiliac Joint Area.

The sacroiliac joint (SIJ) is often considered to be involved when people present for care with low back pain where SIJ is located. However, determining why the pain has arisen can be challenging, especially in the absence of a specific cause such as pregnancy, disease, or trauma, when the SIJ might be identified as a source of symptoms with the help of manual clinical tests. Nonspecific SIJ-related pain is commonly suggested to be causally associated with movement problems in the SIJ(s)-a diagnosis traditionally derived from manual assessment of movements of the SIJ complex. Management choices often consist of patient education, manual treatment, and exercise. Although some elements of management are consistent with guidelines, this Perspective article argues that the assumptions on which these diagnoses and treatments are based are problematic, particularly if they reinforce unhelpful, pathoanatomical beliefs. This article reviews the evidence regarding the clinical detection and diagnosis of SIJ movement dysfunction. In particular, it questions the continued use of assessing movement dysfunction despite mounting evidence undermining the biological plausibility and subsequent treatment paradigms based on such diagnoses. Clinicians are encouraged to align their assessment methods and explanatory models with contemporary science to reduce the risk of their diagnoses and choice of intervention negatively affecting clinical outcomes.

Movement Does Not Promote Recovery of Motor Output Following Acute Experimental Muscle Pain.

Objective: To examine the effect of motor activity on the magnitude and duration of altered corticomotor output following experimental muscle pain. Design: Experimental, pre-post test. Setting: University laboratory. Subjects: Twenty healthy individuals. Methods: Participants were randomly allocated to a Rest or Movement group. The Rest group sat quietly without moving for the duration of the experiment. The Movement group repeated a unimanual pattern of five sequential keystrokes as quickly and as accurately as possible immediately following the resolution of pain. Pain was induced into the right extensor carpi radialis brevis muscle by a bolus injection of 0.5 mL hypertonic saline. Corticomotor output was assessed as motor evoked potentials in response to transcranial magnetic stimulation before, immediately after, and at 10, 20, and 30 minutes following pain resolution. Pain intensity was recorded every 30 seconds using an 11-point numerical rating scale. Results: There was no difference in peak pain intensity (P < 0.09) or duration (P < 0.2) between groups. Corticomotor output was reduced in both groups (P < 0.002) at 10 minutes (P < 0.002), 20 minutes (P < 0.02), and 30 minutes (P < 0.037) following the resolution of pain relative to baseline. There was no difference between groups at any time point. Conclusions: Performance of motor activity immediately following the resolution of acute muscle pain did not alter the magnitude or duration of corticomotor depression. Understanding corticomotor depression in the postpain period and what factors promote recovery has relevance for clinical pain syndromes where ongoing motor dysfunction, in the absence of pain, may predispose to symptom persistence or recurrence.

Australian football players experiencing groin pain exhibit reduced subscale scores of Activities of Daily Living and Sport and Recreation on the HAGOS questionnaire: A case-control study.

OBJECTIVES: To report normative responses to the HAGOS questionnaire for Australian football players and to determine whether any of the HAGOS questionnaire sub scales can differentiate players with and without groin pain. DESIGN: Case-control. SETTING: Clinical setting. PARTICIPANTS: Professional (n = 66) and semi-professional (n = 9) Australian football (AF) players with current groin pain (n = 16) and controls (n = 57) without current groin pain. MAIN OUTCOME MEASURE: The HAGOS subscales were compared between players with and without groin pain using the Wilcoxon rank-sum test with effect sizes (ES) calculated. Floor and ceiling effects were examined. A post-hoc factor analysis was undertaken. RESULTS: Participants with current groin pain showed lower Physical Function of Daily Living (PFDL) and Physical Function in Sport and Recreation (PFSR) subscale scores (p < 0.05, ES: 0.77 and 0.90 respectively). Any groin pain (current and/or historical) lowered the Pain and Quality of Life (QOL) subscale scores (p < 0.05, ES: 0.38 and 0.72 respectively). Factor analysis showed 8 significant factors with one main factor identified representing items describing forceful activities (Eigenvalue = 18.02, Proportion = 0.49). CONCLUSIONS: The HAGOS can distinguish AF players with current groin pain in the PFDL and PFSR subscales but not in the other four subscales. Any current or historical groin pain lowers scores on the QOL and Pain sub scales. LEVEL OF EVIDENCE: Aetiology, Individual Case-Control Study, Level 3b.

Do Australian Football players have sensitive groins? Players with current groin pain exhibit mechanical hyperalgesia of the adductor tendon.

OBJECTIVES: This is the first study to evaluate the mechanical sensitivity, clinical classifications and prevalence of groin pain in Australian football players. DESIGN: Case-control. METHODS: Professional (n=66) and semi-professional (n=9) Australian football players with and without current or previous groin injuries were recruited. Diagnoses were mapped to the Doha Agreement taxonomy. Point and career prevalence of groin pain was calculated. Pressure pain thresholds (PPTs) were assessed at regional and distant sites using handheld pressure algometry across four sites bilaterally (adductor longus tendon, pubic bone, rectus femoris, tibialis anterior muscle). To assess the relationship between current groin pain and fixed effects of hyperalgesia of each site and a history of groin pain, a mixed-effect logistic regression model was utilised. Receiver Operator Characteristic (ROC) curve were determined for the model. RESULTS: Point prevalence of groin pain in the preseason was 21.9% with a career prevalence of 44.8%. Adductor-related groin pain was the most prevalent classification in the pre-season period. Hyperalgesia was observed in the adductor longus tendon site in athletes with current groin pain (OR=16.27, 95% CI 1.86 to 142.02). The ROC area under the curve of the regression model was fair (AUC=0.76, 95% CI 0.54 to 0.83). CONCLUSIONS: Prevalence data indicates that groin pain is a larger issue than published incidence rates imply. Adductor-related groin pain is the most common diagnosis in pre-season in this population. This study has shown that hyperalgesia exists in Australian football players experiencing groin pain indicating the value of assessing mechanical pain sensitivity as a component of the clinical assessment.

Experimental Pelvic Pain Impairs the Performance During the Active Straight Leg Raise Test and Causes Excessive Muscle Stabilization.

OBJECTIVES: The active straight leg raise (ASLR) test is widely used clinically to assess severity of lumbopelvic pain due to decreased stability of the sacroiliac joint (SIJ). This study aimed to bypass the influence of decreased SIJ stability on the ASLR test by investigating the effect of experimental pelvic pain and hyperalgesia on the outcome of the ASLR test. METHODS: Thirty-four healthy participants took part in this randomized crossover study. Pelvic pain was induced by injecting hypertonic saline into the long posterior sacroiliac ligament. Isotonic saline was injected on the contralateral side as control. Pain intensity was assessed on an electronic visual analogue scale. The Likert scores of difficulty performing the ASLR test and simultaneous electromyography of trunk and thigh muscles were recorded before, during, and postpain. Pressure pain thresholds were assessed bilaterally in the pelvic area and lower limb. RESULTS: Compared with the control condition and baseline, hypertonic saline injections caused (P<0.05): (1) higher visual analogue scale scores of the pain intensity; (2) reduced pressure pain thresholds at the injection site and lateral to S2; (3) increased difficulty in performing the ASLR rated on the Likert scale; and (4) bilateral increase in the electromyography activity of stabilizing trunk and thigh muscles during pain. DISCUSSION: These data demonstrate that pain and hyperalgesia in conditions unaffected by biomechanical SIJ impairments change the outcome of the ASLR test toward what is seen in clinical lumbopelvic pain. This may implicate pain-related changes in motor control strategies potentially relevant for the transition from acute into chronic pain.